1. Field of the Invention
The present invention relates to solar-powered irrigation control systems, and in particular to low-energy irrigation systems that operate using electrical energy derived from light and stored in one or more capacitors.
2. Description of the Related Technology
Irrigation systems are used widely in commercial and residential applications. Typical irrigation systems include an irrigation controller connected to one or more irrigation devices (e.g., valves) which provide water to desired locations via an assortment of hydraulic components (e.g., pipes, sprinkler heads, and drip lines). The irrigation controllers control the components to provide desired irrigation in accordance with a programmed schedule. In areas where electrical power is available, most irrigation controllers are powered by alternating current (AC) through a wired connection, or by direct current (DC) which is typically provided by a DC power supply connected to a wired AC power source. In systems with a wired AC or DC power source, the energy efficiency of the irrigation controller is usually not a concern.
In remote locations where a wired AC or DC power source is not readily available, or where placed in locations where providing a wired source is not convenient, some irrigation controllers are configured with a solar power system that converts light energy to electrical energy and stores the electrical energy in a battery contained in the irrigation controller. The irrigation controller uses the battery as a DC power source to power its operations. Some irrigation systems use a combination of one or more batteries with other power storage/providing devices to power the irrigation controller. The energy efficiency of a battery powered irrigation system can be more critical because there is a finite amount of power available at a given time. However, this problem can be generally overcome by using a solar panel and battery sized to generate and store a large amount of power (relative to the expected use), so that energy efficiency of the irrigation controller is again not a concern.
Although widely used, having a battery in an irrigation controller, whether as a stand-alone power storage device or in addition to another power storage device, can be problematic. Rechargeable batteries have a limited lifespan and can be charged and discharged a finite number of times, despite advances in battery technology. An irrigation controller having a battery requires periodic maintenance to change the battery once it is depleted. Such maintenance can be time-consuming and expensive, especially for irrigation systems that are located in remote areas and include numerous irrigation controllers. Also, batteries can leak hazardous material which can erode proximate electrical components and in some cases ruin the irrigation controller. High quality rechargeable batteries can be expensive, heavy, and large, which can impact the design of a compact irrigation controller designed to blend in with its surrounding. It would be beneficial to the art to provide a solar powered irrigation controller that does not require a battery power source to overcome the above-mentioned problems and other problems in the art.